docs: def _get_backends():
      """Retrieve the list of configured service backends."""
      backends = []
      backend_paths = getattr(
          settings, 'MAMA_CAS_SERVICE_BACKENDS',
          ['mama_cas.services.backends.SettingsBackend']
      )
      for backend_path in backend_paths:
          backend = import_string(backend_path)()
          backends.append(backend)
      return backends